import * as http from 'node:http';
import { exec, spawn, ChildProcess } from 'node:child_process';
import * as fs from 'node:fs';
import * as path from 'node:path';
import { fileURLToPath } from 'node:url';
import axios from 'axios';
import { Resend } from 'resend';

const __filename = fileURLToPath(import.meta.url);
const __dirname = path.dirname(__filename);

interface Config {
  RES1_REPO: string;
  GITHUB_PAT: string;
  VERSIONS_DIR: string;
  HEALTH_PORT: number;
  PROD_PORT: number;
  TEST_PORT: number;
  ADMIN_EMAIL: string;
  RESEND_API_KEY: string;
  FROM_EMAIL: string;
}

const CONFIG: Config = {
  RES1_REPO: 'https://github.com/NepsenX/Oracus-AI.git',
  GITHUB_PAT: process.env.GITHUB_PAT || '',
  VERSIONS_DIR: '/app/versions',
  HEALTH_PORT: 7860,
  PROD_PORT: 7000,
  TEST_PORT: 2000,
  ADMIN_EMAIL: 'oracusai.nepsenx@gmail.com',
  RESEND_API_KEY: process.env.RESEND_API_KEY || '',
  FROM_EMAIL: 'onboarding@resend.dev'
};

if (!CONFIG.GITHUB_PAT) {
  console.error('❌ GITHUB_PAT not set!');
  process.exit(1);
}

if (!CONFIG.RESEND_API_KEY) {
  console.warn('⚠️ RESEND_API_KEY not set. Email notifications disabled.');
}

const resend = CONFIG.RESEND_API_KEY ? new Resend(CONFIG.RESEND_API_KEY) : null;

// ============================================================
// EMAIL FUNCTION (only on failure/crash)
// ============================================================
async function sendEmail(subject: string, text: string): Promise<void> {
  if (!resend) {
    console.log(`📧 [SKIP] Email would be sent: "${subject}"`);
    return;
  }
  try {
    const { data, error } = await resend.emails.send({
      from: CONFIG.FROM_EMAIL,
      to: [CONFIG.ADMIN_EMAIL],
      subject: `[Oracus Runner] ${subject}`,
      text: text
    });
    if (error) {
      console.error('❌ Resend error:', error);
    } else {
      console.log(`✅ Email sent! ID: ${data?.id}`);
    }
  } catch (err: any) {
    console.error(`⚠️ Email failed (ignored): ${err.message}`);
  }
}

// ============================================================
// GIT UTILITIES
// ============================================================
function runGitCommand(cmd: string, cwd: string): Promise<string> {
  return new Promise((resolve, reject) => {
    exec(cmd, { cwd }, (error, stdout, stderr) => {
      if (error) reject(stderr || error.message);
      else resolve(stdout.trim());
    });
  });
}

function getRepoUrlWithPat(repoUrl: string): string {
  if (repoUrl.includes('@')) return repoUrl;
  return repoUrl.replace('https://', `https://${CONFIG.GITHUB_PAT}@`);
}

async function getCurrentCommitSha(repoUrl: string): Promise<string | null> {
  try {
    const urlWithPat = getRepoUrlWithPat(repoUrl);
    const output = await runGitCommand(`git ls-remote ${urlWithPat} main`, process.cwd());
    return output.split(/\s/)[0];
  } catch {
    return null;
  }
}

async function cloneOrPull(repoUrl: string, targetDir: string): Promise<void> {
  const urlWithPat = getRepoUrlWithPat(repoUrl);
  if (!fs.existsSync(targetDir)) {
    console.log(`📥 Cloning into ${targetDir}...`);
    await runGitCommand(`git clone ${urlWithPat} ${targetDir}`, process.cwd());
  } else {
    console.log(`🔄 Pulling latest...`);
    await runGitCommand(`git pull`, targetDir);
  }
}

function copyMemoryFolder(srcPath: string, dstPath: string): void {
  const srcMemory = path.join(srcPath, 'memory');
  const dstMemory = path.join(dstPath, 'memory');
  if (fs.existsSync(srcMemory)) {
    if (fs.existsSync(dstMemory)) fs.rmSync(dstMemory, { recursive: true, force: true });
    fs.cpSync(srcMemory, dstMemory, { recursive: true });
    console.log(`📂 Memory copied from ${srcPath} to ${dstPath}`);
  } else {
    console.log(`⚠️ No memory folder found in ${srcPath}`);
  }
}

// ============================================================
// AGENT DEPLOYMENT
// ============================================================
function deployAgent(versionDir: string, port: number): Promise<ChildProcess> {
  return new Promise((resolve, reject) => {
    console.log(`🚀 Starting agent on port ${port} from ${versionDir}...`);
    exec(`npm install && npm run build`, { cwd: versionDir }, (err) => {
      if (err) return reject(`Build failed: ${err.message}`);
      const proc = spawn('npm', ['start'], {
        cwd: versionDir,
        env: { ...process.env, PORT: String(port) },
        stdio: 'pipe'
      });
      proc.stdout.on('data', (data) => console.log(`[AGENT:${port}] ${data}`));
      proc.stderr.on('data', (data) => console.error(`[AGENT ERR:${port}] ${data}`));
      setTimeout(async () => {
        try {
          const res = await axios.get(`http://localhost:${port}/health`, { timeout: 3000 });
          if (res.status === 200) {
            console.log(`✅ Health check passed on port ${port}!`);
            resolve(proc);
          } else reject(`Health check failed on port ${port}`);
        } catch (err: any) {
          reject(`Health check error on port ${port}: ${err.message}`);
        }
      }, 8000);
    });
  });
}

// ============================================================
// STATE
// ============================================================
let prodProcess: ChildProcess | null = null;
let prodVersionPath: string | null = null;
let prodCommitSha: string | null = null;
let isUpdating: boolean = false;

// ============================================================
// FAILED VERSIONS TRACKING (LIMITED TO LAST 100)
// ============================================================
const FAILED_VERSIONS_FILE = '/app/failed-versions.json';
const MAX_FAILED_VERSIONS = 100;

function loadFailedVersions(): string[] {
  try {
    if (fs.existsSync(FAILED_VERSIONS_FILE)) {
      const data = fs.readFileSync(FAILED_VERSIONS_FILE, 'utf-8');
      const parsed = JSON.parse(data);
      if (Array.isArray(parsed)) return parsed;
    }
  } catch (e) {
    console.warn('⚠️ Failed to load failed-versions.json');
  }
  return [];
}

function saveFailedVersion(sha: string): void {
  try {
    let failed = loadFailedVersions();
    // Remove duplicate if exists
    failed = failed.filter(v => v !== sha);
    // Add new at the end
    failed.push(sha);
    // Keep only last MAX_FAILED_VERSIONS
    if (failed.length > MAX_FAILED_VERSIONS) {
      failed = failed.slice(-MAX_FAILED_VERSIONS);
    }
    fs.writeFileSync(FAILED_VERSIONS_FILE, JSON.stringify(failed, null, 2));
    console.log(`💾 Failed version ${sha} saved. Total failed: ${failed.length}`);
  } catch (e) {
    console.error('❌ Failed to save failed version:', e);
  }
}

function isVersionFailed(sha: string): boolean {
  const failed = loadFailedVersions();
  return failed.includes(sha);
}

function clearFailedVersion(sha: string): void {
  try {
    const failed = loadFailedVersions();
    const updated = failed.filter(v => v !== sha);
    fs.writeFileSync(FAILED_VERSIONS_FILE, JSON.stringify(updated, null, 2));
    console.log(`🗑️ Failed version ${sha} removed from tracking list.`);
  } catch (e) {
    console.error('❌ Failed to clear failed version:', e);
  }
}

// ============================================================
// MAIN UPDATE LOGIC (Your Exact Flow)
// ============================================================
async function checkAndUpdate(): Promise<void> {
  if (isUpdating) {
    console.log('⏳ Update already in progress...');
    return;
  }

  isUpdating = true;
  let testProcess: ChildProcess | null = null;
  let testVersionPath: string | null = null;
  let testCommitSha: string | null = null;

  try {
    console.log('🔍 Checking for updates...');

    const latestSha = await getCurrentCommitSha(CONFIG.RES1_REPO);
    if (!latestSha) throw new Error('Could not fetch latest SHA');

    console.log(`📌 Latest SHA: ${latestSha.substring(0, 7)}`);
    console.log(`📌 Current Prod SHA: ${prodCommitSha ? prodCommitSha.substring(0, 7) : 'none'}`);

    // CHECK 1: New code available?
    if (latestSha === prodCommitSha) {
      console.log('✅ No new code. Current version is already running.');
      if (prodCommitSha && isVersionFailed(prodCommitSha)) {
        console.log(`🔄 Version ${prodCommitSha.substring(0, 7)} was previously failed but now running. Clearing from failed list.`);
        clearFailedVersion(prodCommitSha);
      }
      isUpdating = false;
      return;
    }

    // CHECK 2: Is this new version previously failed?
    if (isVersionFailed(latestSha)) {
      console.log(`⏳ Version ${latestSha.substring(0, 7)} is marked as FAILED in history.`);
      console.log('🔄 Waiting for a NEW version after this failed one.');
      isUpdating = false;
      return;
    }

    // NEW VERSION DETECTED → Deploy on port 2000
    console.log(`🆕 New version: ${latestSha.substring(0, 7)}. Deploying on port ${CONFIG.TEST_PORT}...`);

    testCommitSha = latestSha;
    testVersionPath = path.join(CONFIG.VERSIONS_DIR, `v2_${Date.now()}`);
    await cloneOrPull(CONFIG.RES1_REPO, testVersionPath);

    // TEST ON PORT 2000
    testProcess = await deployAgent(testVersionPath, CONFIG.TEST_PORT);
    console.log(`✅ V2 passed health check on port ${CONFIG.TEST_PORT}!`);

    // COPY MEMORY FROM 7000 → 2000
    if (prodVersionPath) {
      copyMemoryFolder(prodVersionPath, testVersionPath);
    } else {
      console.log('⚠️ No previous version. Starting fresh without memory copy.');
    }

    // STOP TEST (2000)
    if (testProcess) {
      console.log('🛑 Stopping test agent on port 2000...');
      testProcess.kill('SIGTERM');
      await new Promise(resolve => setTimeout(resolve, 2000));
      if (!testProcess.killed) testProcess.kill('SIGKILL');
      testProcess = null;
    }

    // PROMOTE TO 7000
    console.log(`🚀 Promoting to production port ${CONFIG.PROD_PORT}...`);
    const newProdProc = await deployAgent(testVersionPath, CONFIG.PROD_PORT);

    // Stop old production
    if (prodProcess) {
      console.log('🛑 Stopping old production on port 7000...');
      prodProcess.kill('SIGTERM');
      setTimeout(() => {
        if (!prodProcess?.killed) prodProcess?.kill('SIGKILL');
      }, 3000);
    }

    // Update state
    prodProcess = newProdProc;
    prodVersionPath = testVersionPath;
    prodCommitSha = testCommitSha;
    testVersionPath = null;
    testCommitSha = null;

    // Clear failed flag if this version was previously failed
    if (prodCommitSha && isVersionFailed(prodCommitSha)) {
      clearFailedVersion(prodCommitSha);
    }

    console.log(`✅ Successfully deployed V2 (${latestSha.substring(0, 7)}) on port ${CONFIG.PROD_PORT}`);

  } catch (error: any) {
    console.error('❌ Deployment failed:', error);

    // Stop test process (port 2000) if running
    if (testProcess) {
      console.log('🛑 Stopping failed test agent on port 2000...');
      testProcess.kill('SIGTERM');
      setTimeout(() => {
        if (!testProcess?.killed) testProcess?.kill('SIGKILL');
      }, 2000);
      testProcess = null;
    }

    // Save the failed version (with size limit)
    if (testCommitSha) {
      console.log(`💾 Saving failed version ${testCommitSha.substring(0, 7)} to tracking list.`);
      saveFailedVersion(testCommitSha);
    }

    // Send email notification
    await sendEmail('Deployment FAILED', `Version: ${testCommitSha ? testCommitSha.substring(0, 7) : 'unknown'}\nError: ${error.message}\nPort 7000 is unchanged.`);

    // Keep old production running
    if (prodProcess) {
      console.log('🔄 Keeping old version running on port 7000.');
    } else {
      console.log('⚠️ No previous version available. Port 7000 is empty.');
    }

    // Clean up failed test version directory
    if (testVersionPath && fs.existsSync(testVersionPath)) {
      try {
        fs.rmSync(testVersionPath, { recursive: true, force: true });
        console.log(`🧹 Cleaned up failed test directory: ${testVersionPath}`);
      } catch (e) {
        // ignore
      }
    }

  } finally {
    isUpdating = false;
  }
}

// ============================================================
// HTTP SERVER (Port 7860 - UptimeRobot)
// ============================================================
const server = http.createServer(async (req, res) => {
  const url = new URL(req.url || '/', `http://${req.headers.host}`);

  if (url.pathname === '/') {
    res.writeHead(200, { 'Content-Type': 'text/plain' });
    res.end('Oracus Runner is Alive!');
    setImmediate(() => checkAndUpdate());
  } else if (url.pathname === '/force-update') {
    res.writeHead(200);
    res.end('Force update triggered.');
    setImmediate(() => checkAndUpdate());
  } else if (url.pathname === '/status') {
    const failed = loadFailedVersions();
    res.writeHead(200, { 'Content-Type': 'application/json' });
    res.end(JSON.stringify({
      prodRunning: prodProcess !== null,
      prodVersion: prodCommitSha ? prodCommitSha.substring(0, 7) : 'none',
      prodVersionPath: prodVersionPath ? path.basename(prodVersionPath) : 'none',
      isUpdating,
      failedVersions: failed.map(s => s.substring(0, 7))
    }, null, 2));
  } else {
    res.writeHead(404);
    res.end('Not Found');
  }
});

server.listen(CONFIG.HEALTH_PORT, '0.0.0.0', () => {
  console.log(`✅ Health server running on port ${CONFIG.HEALTH_PORT}`);
  console.log('⏳ Initial setup...');
  checkAndUpdate();
});

// ============================================================
// CRASH HANDLING
// ============================================================
process.on('uncaughtException', (err) => {
  console.error('💥 Uncaught Exception:', err);
  sendEmail('CRASH - Uncaught Exception', err.stack || err.message);
});

process.on('unhandledRejection', (reason) => {
  console.error('💥 Unhandled Rejection:', reason);
  sendEmail('CRASH - Unhandled Rejection', String(reason));
});